The present invention relates to the field of programmable input and output interfaces and in particular to an integrated circuit that can be programmed to accommodate various input/output signals with different characteristics at the same time and through the same interface.
For any computer-controlled electrical system, the handling of input and output between components of the system is an important aspect of the system. An interface between components of a system can convert or condition an output signal from one component to become a compatible input signal in another component. This conversion or conditioning must be performed while maintaining the signal""s integrity and accuracy.
Often, an input/output interface will have to coordinate input and output signals with extremely varied signal characteristics. For example, one component can have analog signals that need to be converted into digital signals in order to be analyzed by another component. In another instance, typical for aircraft, analog signals from one component can have a voltage range as great as (xe2x88x9215 to +28) volts while another component in the system has a voltage range of +/xe2x88x925 millivolts. Other situations entail having components that utilize both differential and single-ended signals that have to be input to another component.
Given the wide variety of signal characteristics that can exist within a given system, input/output interface designs are typically developed to apply to a specific system. In particular, for systems on an aircraft, sensors on the aircraft can produce widely different output signals that have to be converted and conditioned in order to be processed by the aircraft computers. Typically, a different input/output interface is developed for every sensor to produce a digital stream of data readable by the aircraft computers.
Redesigning the input/output interface every time a new sensor is used wastes valuable time and money, as the designer must gain expertise with these sensors before designing the new interface. As such, there exists a need for a compact device that can be easily incorporated into a component system and programmable to handle a multitude of signals of varied characteristics to create a single standard interface between components of that system.
This invention comprises a configurable integrated circuit (IC) which is advantageously a single miniature chip to coordinate input and output (I/O) signals. The chip performs signal conditioning, analog-to-digital and digital-to-analog conversion. Both single-ended signals and differential signals can be handled at each channel of the chip. In addition, each channel is configurable to accept input signals or generate output signals. This invention enables the reuse of I/O hardware across multiple applications and reduces chip count, board space and connections and thus increases design reliability.
In one illustrative embodiment an input/output interface within a computer controlled electrical system comprises a plurality of signal conditioning cells to provide a physical interface for electrical signals in the system where each of the plurality of signal conditioning cells is capable of handling signals with different characteristics. A signal conversion cell connected to the signal conditioning cells is capable of converting each of the electrical signals on the plurality of channels to become a digital data value for the computer. The plurality of signals includes discrete signals, analog signals, differential signals, or single-ended signals.